Generally, the industry of semiconductor manufacturing involves highly complex techniques for fabricating integrating circuits using semiconductor materials which are layered and patterned onto a substrate, such as silicon. Due to the large scale of circuit integration and the decreasing size of semiconductor devices, the fabricated devices have become increasingly sensitive to defects. That is, defects which cause faults in the device are becoming increasingly smaller. The device can generally be required to be fault free prior to shipment to the end users or customers.
Various inspection systems are used within the semiconductor industry to detect defects on a semiconductor reticle or wafer. One type of inspection tool is an optical inspection system. In optical inspection systems, one or more radiation beams are directed towards the semiconductor wafer and a reflected and/or scattered beam is then detected. The detected beam may then be used to generate a detected electrical signal or an image, and such signal or image is then analyzed to determine whether defects are present on the wafer.
In a specific inspection application, the side of a wafer is imaged to obtain an image of the edge region of such wafer. There is a continuing need for improved inspection techniques and apparatus for imaging such edge regions.